The Bug:

Sculk sensors are not activated upon making your pet sit or stand.

Steps to Reproduce:

• Tame any pet that is able to be sat or stood.
• Make it sit or stand. (Right-Click by Default).
  →  Notice how the sculk sensor does not activate upon doing this.

Additional Information:

Quote from the 20w49a Changelog, "A vibration is anything that causes physical motion". I would definitely consider this as physical motion, as your pet is physically moving.